Good for green (and other colors).

Contrary to popular belief, overcast days are better for shooting color than bright, sunny ones. There are two reasons that's so. One is, there's less "glare" (specular reflection) on overcast days. The other, color film (yeah, I said film) has a narrower exposure latitude than black-and-white film, which means it does not respond as well to high-contrast compositions. Digital color does not seem to suffer so much in contrasty situations as film does but, as a general rule, the limitations of color film have educated us to expect lower contrast in color images.